A study in the Lao People’s Democratic Republic indicates that low-cost, village-wide efforts to improve sanitation have powerful benefits that cascade across income and age groups.
Hand sanitizer. Face masks. Air filters. Hygiene has taken center stage for the past year as a critical defense against COVID-19. Sanitation and hygiene are critical not just for preventing transmission of respiratory disease, but for fighting the spread of gastrointestinal infections that stunt children’s growth and cognitive development and limit their lifetime economic potential.
Global access to basic sanitation facilities improved from 56% in 2000 to 74% in 2017, according to a World Health Organization/UNICEF study. Despite this major progress toward achieving Sustainable Development Goal 6 – universal access to clean water and sanitation – nearly 700 million people still practice open defecation today.
Due to their remoteness and poverty, rural communities lag urban areas in access to modern sanitation facilities that separate people from human waste, such as flush toilets and septic tanks. This allows spread of diarrheal diseases, which have dire consequences for the health of the next generation.
In the absence of public toilets, improving rural sanitation requires sizeable private hardware investments that are difficult for the poorest households to afford. Sanitation subsidies have demonstrated the ability to promote toilet use in several settings, but they are often costly to administer. More experimentation is needed to identify cost-effective programs that improve water, sanitation, and hygiene in remote communities.
To investigate new ways to improve rural sanitation and the relationship between local sanitation and the health of young children, we worked with 160 villages in southern Lao People’s Democratic Republic. In these areas, we ran randomized controlled trials, basically applying the experimental approach of clinical trials to a social science problem.
We wanted to find out if providing incentives to an entire village rather than specific families would be cost-effective in encouraging use of hygienic toilets, and if a temporary sanitation campaign could have a lasting effect on children’s growth. To find the answers, we partnered with the government’s National Center for Environmental Health and Water Supply, the organization East Meets West, World Bank and Australia’s Department of Foreign Affairs and Trade (DFAT).
In addition to testing private incentives that were smaller than in previous studies (household rebates of $20 per toilet installed), we designed a collective incentive that delivers rewards at the village level. Under the collective incentive scheme, village committees were awarded about $400 for eradicating open defecation in their village. That award could be used on any development project of the committee’s choice, and village leadership was left to its own devices to motivate toilet use. The 160 villages were randomly assigned to be eligible for private or collective incentives.
Following-up with the villages three years after the program began and one year after the program concluded, we found that both types of incentives increased village toilet ownership substantially and by about the same amount (25%). But they assisted two different subgroups. The household incentives helped poor households, while the collective incentives increased toilet ownership of non-poor households. The village incentives were more cost-effective and less administratively burdensome, but did not reach the most vulnerable households in villages.
Having observed this large improvement in sanitation, we turned to our second research question on whether improvements in children’s health were achieved due to the program. Despite the physiological link between hygiene, disease, and growth, there are few studies establishing a causal effect of sanitation programs on children’s growth.
Based on measurements of children age 3-5 at the conclusion of the study, we found that every 10 percentage point improvement in village toilet ownership increased children’s height by 0.1 standard deviations, and that overall the program increased children’s height by half a centimeter. These gains were not limited to children in households that had a toilet of their own. It was local sanitation, not a household’s own sanitation, that improved height.
In fact, there were height gains even for households that continued to practice open defecation as long as their village’s sanitation improved. This is strong evidence of the health externalities that we have become acutely aware of during the pandemic: when one household improves its hygiene (in this case by buying a toilet), neighboring households’ benefit.
We also find that even small improvements in village sanitation helped the most vulnerable children, with the village stunting rate falling by 3 percentage points for every 10-percentage point improvement in toilet ownership. Just like how each person vaccinated against COVID-19 lowers the risk of transmission for all, the life-changing benefits of sanitation kick in for families that don’t directly benefit from sanitation programs well before total elimination of open defecation is achieved.
This work has two main takeaways for water, sanitation and hygiene programming. First, small, untargeted financial incentives (the collective incentives costed US$6 per toilet built) can support improved sanitation in rural areas, although larger and targeted incentives are needed to assist the poorest households.
Second, investing in toilets (and complementary water, sanitation and hygiene investments like improved drinking water sources) can be highly equitable even if they do not directly affect the poor, because of the strong community-wide benefits of reducing open defecation.